Solvent-UV hybrid inkjet ink for aluminum beverage can decoration

Abstract

A hybrid inkjet ink comprising a water miscible organic solvent, a UV radiation-curable material and appropriate photoinitiator, and an epoxide-containing material and printed decorations produced by applying the inkjet ink images to an aluminum substrate.

Claims

1. A hybrid inkjet ink comprising, in percent by weight based on the weight of the hybrid inkjet ink: about 3-49% of gamma-butyrolactone; about 3-80% by weight of a UV radiation-curable material and a photoinitiator, the UV radiation-curable material comprising a monofunctional UV radiation-curable monomer, which is 4-tert-butylcyclohexylacrylate, 2-phenoxyethyl acrylate, or a combination thereof; and a trifunctional UV radiation-curable monomer, which is propoxylated(3)trimethylopropane triacrylate; a resin; and about 1-30% by weight of neopentyl glycol diglycidyl ether.

2. The hybrid inkjet ink of claim 1, wherein the UV radiation-curable material further comprises a difunctional UV radiation-curable monomer selected from the group consisting of aliphatic, cycloaliphatic, polyester, polyurethane, and ethylene/propylene glycol diacrylates.

3. The hybrid inkjet ink of claim 2, wherein the difunctional UV radiation-curable monomer is hexanediol diacrylate, dipropylene glycol diacrylate, or a combination thereof.

4. The hybrid inkjet ink of claim 1, wherein the resin has a molecular weight of about 1000-50,000 Daltons.

5. The hybrid inkjet ink of claim 1, wherein the resin is selected from the group consisting of polyols, acrylated polyesters, acrylated polyurethanes, and a combination thereof.

6. The hybrid inkjet ink of claim 1, further comprising a colorant.

7. A printed decoration comprising: an aluminum substrate; and the hybrid inkjet ink according to claim 1 applied to the aluminum substrate using an inkjet printer.

8. A method of producing a printed decoration, applying the hybrid inkjet ink of claim 1 to an aluminum substrate using an inkjet printer to form an image on the aluminum substrate; irradiating the image with UV light to achieve a partial cure of the image, pinning the image to the aluminum substrate while leaving unevaporated solvent in place within the image; applying an overprint varnish to intermix with the unevaporated solvent in the image; and heating the image to drive off the unevaporated solvent and produce a full cure of the image as a printed decoration on the aluminum substrate.

9. The method of claim 8, wherein the overprint varnish includes an aqueous carrier.

10. The method of claim 8, wherein the overprint varnish includes an organic carrier.

11. The method of claim 8, wherein the aluminum substrate is an outer surface of an aluminum beverage can.

12. The method of claim 8, wherein the printed decorations has a thickness exclusive of overprint varnish of about 1 to 12 m.

13. The method of claim 8, wherein the printed decorations has a thickness exclusive of overprint varnish of about 1-8 m.

14. A hybrid inkjet ink comprising, in percent by weight based on the weight of the hybrid inkjet ink: about 20% of gamma-butyrolactone; about 13% of 4-tert-butylcyclohexylacrylate; about 4% of 2-phenoxyethyl acrylate; about 6% of propoxylated(3)trimethylopropane triacrylate; about 12% of a resin; and about 13% of neopentyl glycol diglycidyl ether.

Description

EXAMPLES

(1) The following examples are presented for purposes of illustration and are not intended to be exhaustive or limiting of any embodiment of the invention.

(2) 1. Adhesion to Aluminum Substrate

(3) The test specimens were successfully necked cans with inkjet-applied decoration and an overprint varnish top coat. An ASTM standard test method D3359-09 was used to measure and examine the adhesion of inkjet-applied hybrid ink. A hard metal straight edge was used to make straight cuts with a sharp razor blade to form intersecting 7 to 8 crosshatched cuts in selected areas of the body and neck of the cans. The tape applied was a 0.75 wide transparent Scotch Brand Tape, Cat 600.

(4) The crosshatch adhesion tests on both the necked areas of the can specimens and on the bodies of the can specimens for CMYK image hybrid coatings did not show any adhesion failure and had outstanding adhesion ratings of 4B-5B, before and after pasteurization.

(5) 2. Gloss Level

(6) An ASTM standard test method D523-08 was used to measure the specular gloss of nonmetallic specimens for glossmeter geometries of 20, 60, and 85 using two specimens: 1) a hybrid black ink prepared in accordance with embodiments of the invention and applied using an inkjet printer, and 2) a commercial black beverage can coating prepared using conventional offset printing. A black hybrid inkjet ink as follows was used:

(7) TABLE-US-00001 Material Type Percent by Weight 4-tert-butylcyclohexyl acrylate (monomer) 13 2-phenoxyethyl acrylate (monomer) 4 Propoxylated (3) Trimethylopropane Triacrylate 6 (trifunctional monomer) Resin 12 Amine Synergist 8 Antioxidant and thermal stabilizer blend 1 Surfactant 1 Photoinitiator Norrish Type I 3.5 Photoinitiator Norrish Type II 3.5 Black Pigment Dispersion (colorant) 15 Gamma-butyrolactone (solvent) 20 Neopentyl glycol diglycidyl ether (epoxide) 13 100

(8) The 20 geometry is advantageous for comparing specimens having 60 gloss values higher than 70. The 60 geometry is used for inter-comparing most specimens and for determining when the 20 geometry may be more applicable. The 85 geometry is used for comparing specimens for sheen or near-grazing shininess; it is most frequently applied when specimens have 60 gloss values lower than 10.

(9) The following results were obtained:

(10) TABLE-US-00002 Gloss Level Commercial Hybrid Angle Black Black 20 57.6 66.7 60 87.4 89.9 85 96.6 94.4

(11) This data demonstrates that the hybrid inkjet black ink coating can produce gloss levels commensurate with those achieved using conventional offset printing processes. In other words, the new hybrid ink is shown here to enable inkjet printing on aluminum cans to produce gloss levels commensurate with those achieved in conventional offset printing processes thereby delivering all of the benefits of inkjet printing to the can printing process.